Catheters are tube-like medical devices that are inserted into a body organ or blood vessel for diagnostic or therapeutic reasons. One of the therapeutic procedures applicable to the present invention is known as percutaneous translumenal angioplasty (PTA). During such a procedure, a catheter may be inserted through the skin and traverse long distances through vessels. The more fragile or tortuous tissue of these structures may be easily irritated, perforated, or otherwise damaged by the catheter tip. Furthermore, a catheter may be required to cross an already-stented vessel segment. Particularly in small vessels, the danger exists that the catheter may become entangled with the existing implant struts. This may result in damage to the stent, damage to the surrounding tissue, or damage to the catheter.
Catheters must have sufficient stiffness to be pushed long distances through vessels as well as sufficient rigidity to provide torsional control. However, stiffness or rigidity in the catheter tip poses the danger of puncturing or otherwise damaging a vessel as it twists through the vascular system as discussed above. This problem has been addressed in the past by forming the distal end of the relatively rigid catheter with a relatively soft tip which is either atraumatic or significantly less traumatic to vessel wall tissue than the more rigid material forming the body of the catheter. Examples of such soft tip catheters are known in the art.
To move a catheter through the vascular system more easily, the ends of the soft tips are often tapered. The tapering provides a gradual change in diameter along the length, while the material transition provides a change in durometer between the soft tip and the main tubular portion of the catheter. However, the tapered end has limited benefits when approaching a stented sharp turn, such as a renal ostium with in-stent restenosis being approached via the aorta. The symmetric nature of the tapered end does not provide any specific directional benefit. The present invention provides an improvement towards the resolution of this problem.